Ions of uranium, europium, neodymium, terbium and lots of other stuff can fluoresce.
In this video I show a lot of them and also try to explain in simple terms how it works.
Full music credit:
Kevin MacLeod
www.incompetech.com
All under CC license.
Tracks used:
0:30 - 0:50
3:03 - 3:43
4:59 - 5:15
'Darkness is Coming'
ISRC: USUAN1100584
1:53 - 2:08
'Night Cave'
ISRC: USUAN1100446
4:30 - 4:58
'Bathed in the Light'
ISRC: USUAN1100308
Bonus info:
I use a generic 18 watt longwave UV-blacklight in this video - not the dangerous shortwave UV even though it could give even better results.
Lots of the stuff can be bought on eBay, like
Onyx Metall myworld.ebay.co.uk/onyxmetall
The little test tube with quinine in the beginning is a sample of tonic water that I tried to boil down to concentrate the quinine more. It didn't work out well - lots of sugar in the drink so it just turns into a brown syrup and doesn't really fluoresce more.
Be careful with most of the stuff in the video. Always search for the MSDS for a chemical before you buy it. Especially Rhodamine B is dangerous and can ruin your eyes - wear safety glasses and gloves or even better: stay away from it.
The radioactive minerals also needs to be treated with respect.
It is often the outer most electrons that can be excited - the valence electrons. In the rare earth metals it can happen with inner electrons though - like in neodymium.
All the europium samples are europium oxide.
I believe the LEGO pieces are not only fluorescent but also so-called LISA plastic. LISA is short for 'licht-sammeln' which is German for 'light-gathering'. It is plastic with high internal reflection so the light is transmitted inside the plastic and send out of the edges - like optical fiber cables. But LEGO likes to keep their secrets so it's just my guess. Almost all transparent LEGOs are made of polycarbonate - which LISA plastic also can be. Normal LEGO is made of ABS.